The present invention relates to an eye characteristic measuring apparatus provided with a projection system for projecting a fine light source image onto a fundus of an eye to be detected and a wavefront detection system for detecting a wavefront of a luminous flux emitted from the inside of a pupil of an eye to be detected by a reflected light from the fundus.
In an eye characteristic measuring apparatus in the prior art, such an apparatus is known that a wavefront of luminous flux is detected where luminous flux from a point source formed on the fundus is transmitted within a pupil of an eye to be detected, and the spherical degree, the astigmatism degree, the astigmatism axis, as well as aberration characteristics of higher order are detected.
In such an eye characteristic measuring apparatus in the prior art, a problem exists in that since a point source is projected onto a fundus, when only a reflected light from one point on the fundus is caught, measurement results of a wavefront are dispersed due to difference of the projection positions affected by a blood vessel on the fundus or the like, and thus the measurement results with high accuracy cannot be obtained.
Therefore it has been proposed that a reflection member for deflecting luminous flux into a common optical path of a projection system and a wavefront detection system is disposed, and while position of a point source image projected onto a fundus is varied, an averaged wavefront from each projection position is detected, and dispersion depending on the projection position is removed, whereby the measurement accuracy is improved.
In the prior art as above described, however, since luminous flux is deflected using a reflection optical element, not only constitution for a reflection surface to be vibrated finely is necessary, but also an optical element to return the optical axis for the reflection optical element is necessary. Thus the optical system is complicated inevitably and also the optical adjustment during assembling is quite difficult.
The present invention intends to solve the problems in the prior art, and is characterized in that a deflection prism to deflect a transmitted luminous flux is used as a deflection optical element, and in order that aberration components such as astigmatism generated in the deflection prism are removed, at least one surface of the deflection prism is made an aberration correction transmission surface such as a aspherical surface.
According to the present invention, since at least one transmission surface of the deflection prism is made an aberration correction surface, the deflection prism can be applied as a deflection member in such an apparatus for the first time, and the present invention is advantageous in that only if the deflection prism arranged within the optical path is rotatable about the optical path simply, the optical axis can be inclined and also the optical system can be made quite simple constitution
The present invention is a distance measuring apparatus in which a projection system irradiates a measurement luminous flux toward a measurement object, and in a light receiving system, a reflection luminous flux reflected by the measurement object is received by light receiving conversion means, and based on the reflection luminous flux received by the light receiving conversion means, and the distance from the measurement position to the measurement object is measured, wherein an attenuation filter adjusts a light quantity of luminous flux incident to the light receiving conversion means, and deflection means is provided in at least a part of the attenuation filter.